preparation

Mix butter and sugar in small bowl to blend. Spread on one side of bread slices. Place 2 slices, buttered side down, on plate. Skewer 4 marshmallows on each of 2 skewers; hold skewers over open flame and toast until marshmallows are blackened in spots, about 10 seconds. Divide marshmallows between bread slices on plate, leaving 1-inch border. Sprinkle chocolate chips over marshmallows, dividing equally. Top with banana. Cover with remaining bread, buttered side up, pressing slightly.